Venezuelan Equine Encephalitis Vaccine strain TC-83 (VEE) reproducibly produces teratogenic effects in CNS tissue of fetal rhesus monkeys when inoculated intracerebrally into genic effects in CNS tissue of fetal rhesus monkeys when inoculated intracerebrally into 100-day fetuses. This presents an opportunity to study the pathogenesis of viral-induced micrencephaly, hydrocephalus, porencephaly and cataracts. Simian cytomegalovirus in rhesus monkeys (Rh-CMV): We have produced congenital infection and disease in rhesus monkey fetuses after intrauterine inoculation of Rh-CMV in seropositive mothers. Western Equine Encephalitis (WEE): Fetal rhesus monkeys were inoculated intracerebrally with an experimental vaccine strain of WEE virus. All animals developed micrencephaly. Twelve of 16 monkeys developed ex-vacuo hydrocephalus. All virus-inoculated fetuses developed WEE virus antibody. Virus could not be recovered at the time of delivery. Congenital Toxoplasmosis: In order to develop a nonhuman primate model for congenital toxoplasmosis, we screened several species of nonhuman primates and concluded that patas Erythrocebus patas is the monkey most suitable for studies of acquired toxoplasmosis. These animals were readily infected by oral administration of toxoplasma cysts.